Directions: Fill in the blank with the appropriate word given in the options.

Their marriage has been a/an_______one.

"A happy" works grammatically because happy begins with a consonant sound. While "an industrious" would also be grammatically correct and meaningful for describing a marriage, "industrious marriage" is an uncommon collocation. "Happy marriage" is a standard, natural English expression for describing a successful, positive marriage. "Too" and "lazy" don't make semantic sense in this context.