The fortieth odd number is
81
39
79
41
and the sum of the first forty odd numbers is
80
1600
158
6241

1) Third Option is correct.

2)  Second Option is correct.

Step-by-step explanation:

Since we have given that

odd numbers are as follows:

1, 3, 5, .........................

so, first term = a = 1

d = common difference = 3-1=2

n =  number of terms = 40

As we know that it forms an "Arithmetic Progression ":

so, the fortieth odd number is 79.

Hence, Third Option is correct.

Now, we need to find the first forty odd numbers :

As we know the formula :

Hence, Second Option is correct.  

c

step-by-step explanation: