Hello!
The answer is:
d) usé (used referred to the first person)
Why?
We are given a Spanish sentence which refers to the use of a sunscreen or sun protection cream, but the action was in the past, meaning that we need to find the equivalent verb that fits with the sentence.
The sentence is:
Yo ________ una crema solar.
I __________ a sun protection cream.
We have that the best option for the sentence is "usé" because the sentence is in the first person, "yo usé" is translated to "I used", so, the sentence will be:
Yo usé una crema solar.
I used a sun protection cream
Hence, the correct option is: d) usé (used referred to the first person)
Have a nice day!