El dia que Paula llegó a España, __ mucho frio. (Hacia/Hizo)

El dia que Paula llegó a España, hizo mucho frio.

hizo

Explanation:

The word hacia and the word hizo are both past tense forms of hacer

Hizo is in the preterite tense form whereas hacia is in the imperfect form

What is the main difference between preterite and imperfect form?

Preterite tense is usually used to refer to an event that happened at a specific time or specific place

Ex.

In English - On Friday she made a sandwich

In Spanish - El Viernes se hizo un sandwich

made is the past tense of make

Because its referring to a past tense adjective you would use the preterite tense (or hizo)

Imperfect tense is used to describe an ongoing event without a specific time period in the past

Ex.

In English - She was making a sandwich on Friday

In Spanish - ella estaba haciendo un sandwich el viernes

making is an ongoing adjective.

because its an ongoing event you would use the imperfect tense (or haciendo)

Now lets get back to the question

El dia que Paula llegó a España, __ mucho frio. which translates to

The day Paula arrived in spain ___ was very cold

The word arrived is past tense Which means that we would be using the preterite of hacer (or hizo)

Now if it was

On the day that paula arriving in spain, it was very cold

Then we would use hacia and it would be

El dia que paula llegaba a espana hacia mucho frio

Hizo

Explanation:

The word hacia and the word hizo are both past tense forms of hacer

Hizo is in the preterite tense form whereas hacia is in the imperfect form

What is the main difference between preterite and imperfect form?

Preterite tense is usually used to refer to an event that happened at a specific time or specific place

Ex.

In English - On Friday she made a sandwich

In Spanish - El Viernes se hizo un sandwich

made is the past tense of make

Because its referring to a past tense adjective you would use the preterite tense (or hizo)

Imperfect tense is used to describe an ongoing event without a specific time period in the past

Ex.

In English - She was making a sandwich on Friday

In Spanish - ella estaba haciendo un sandwich el viernes

making is an ongoing adjective.

because its an ongoing event you would use the imperfect tense (or haciendo)

Now lets get back to the question

El dia que Paula llegó a España, __ mucho frio. which translates to

The day Paula arrived in spain ___ was very cold

The word arrived is past tense Which means that we would be using the preterite of hacer (or hizo)

Now if it was

On the day that paula arriving in spain, it was very cold

Then we would use hacia and it would be

El dia que paula llegaba a espana hacia mucho frio