To form the present participle, drop the ending of the infinitive verb and then add
a.
-iendo to -ir verbs and -ando to -ar and -er verbs
b.
-ando to -ar verbs and -iendo to -er and -ir verbs
c.
-ando to -ar and -ir verbs and -iendo to -er verbs
d.
-iendo to -ar verbs and -ando to -er and -ir verbs

B. -ando to -ar verbs and -iendo to -er and -ir verbs.

Explanation: In Spanish, present participles are verb forms used to express continuous or ongoing actions, its called "gerundio" and its also used in compound verb forms.

-AR verbs  

amar : amando, estoy amando.

saltar: saltando, está saltando.

trepar: trepando, están trepando.

-ER verbs

temer: temiendo, estoy temiendo.

romper: rompiendo, está rompiendo.

beber: bebiendo, están bebiendo.

-IR verbs

salir: saliendo, estoy saliendo.

rugir: rugiendo, está rugiendo.

subir: subiendo, están subiendo.