Final answer:
The current height of Francesca's sunflower is 6.142 feet.
Step-by-step explanation:
To find the current height of Francesca's sunflower, we need to add the growth from April to July to the initial height in April.
Francesca's sunflower was 1.75 feet tall at the end of April. It grew 4.392 feet from then until the end of July. So, the current height of the sunflower is 1.75 + 4.392 = 6.142 feet.
Therefore, the answer is 6.142 feet (option a).