Answer: Maturity
Explanation: Maturity stage of product in life cycle is described as level in which sale of product grows till top and then tends to decrease. Product at this stage gets well acknowledged in the market and sale of that product becomes high.
After a long period in market ,eventually the product sale starts to slow down as it has already been introduced and well-known. According to situation in the question, liquid soap is in the maturity phase of product life cycle as many similar and efficient products are introduced in market which cause it to face the increased competition.
Thus, steps like distribution of product immensely, position defense scheme for settling the product in customer's mind etc are used by producers so that sale does not decline.