Select the synonym of
to lash

Let's look at the definitions of the words:
to lash: To strike with a whip; or to criticize harshly/punish severely.

to endear: Make dear or beloved.

to fondle: Stroke or caress lovingly.

to chastise: Rebuke or punish severely; criticize harshly.

to snuggle: Settle or move into a warm, comfortable position.

Since both lash and chastise mean to punish or criticize severely, they are synonyms.