Conlan wants to answer the question, “does phosphorus affect tomato fruit production? ” which statement represents a hypothesis that he can test to answer his question?
if phosphorus affects tomato fruit production, then tomatoes that are fertilized with phosphorus will have larger leaves.
if phosphorus affects tomato fruit production, then phosphorus should be added to the soil during planting.
if phosphorus affects tomato fruit production, then adding phosphorus to the soil will make tomatoes taste better.
if phosphorus affects tomato fruit production, then plants that are fertilized with phosphorus will produce more tomatoes.

The correct option is D.  A hypothesis that he can test to answer his question is 'If phosphorus affects tomato fruit production, then plants that are fertilized with phosphorus will produce more tomatoes.'

Explanation:

A hypothesis is a statement that is proposed in response to a question and further investigations are made to validate it. As the question is asking about the effect of phosphorus on tomato fruit production so options A, B and C would be incorrect.

Option A is a statement proposed for the effect of phosphorus on tomato leaves rather than tomato fruits. Hence, it is incorrect.

Option B is a statement that doesn't determine the effects of phosphorus on the tomato fruit, hence statement B is also incorrect.

Option C doesn't justify the question either because it proposes the effect of phosphorus on the taste of tomato rather than the tomato production.

Hence, option D is the most accurate hypothesis for the question.