We have slept in the desert in the rain.
The sentence we are looking for is in past tense (preterite).
A) Hemos dormido en el desierto en la lluvia. - "We have slept in the desert in the rain." - Preterite tense (dormido); this sentence is correct.
B) Dormimos en el desierto en la lluvia. - "We sleep in the desert in the rain." - Present tense; this is not the tense we need.
C) Tenemos dormir en el desierto en la lluvia. - "We have sleep in the desert in the rain." - Grammatically incorrect; this can't be the right option.
D) Hemos durmiendo en el desierto en la lluvia. - "We have been sleeping in the desert in the rain." - Imperfect tense; this is the wrong tense.
Answer:
A) Hemos dormido en el desierto en la lluvia.
