Ritika is concerned that her GIS benefit may be reduced this year due to the amount of income she is receiving. In 2020, she had the following income sources and amounts: CPP pension ( $5,700), CPP survivor benefit ($1,000), OAS pension ($6,400), TFSA withdrawals ($8,000), part-time employment income ($3,000) and a deceased spouse pension benefit ($2,800). Which of these income sources will be used by Canada Revenue Agency to calculate Ritika's GIS benefit for 2021? CPP pension, CPP survivor benefit, OAS pension All of them CPP pension, CPP survivor benefit, OAS pension, part-time employment income, deceased spouse's pension benefit CPP pension, CPP survivor benefit, deceased spouse's pension